Forming surface relief patterns on poly(olefin sulfone) polymer layers by electron beam resist methods are well known and are utilized for a variety of applications. For example, poly(1-methyl1-cyclopentene sulfone) has been used for audio/video recording applications and is more fully described in U.S. Pat. Nos. 3,935,331 and 3,935,332 by Poliniak et al; poly(1-butene sulfone) has been employed for integrated circuit mask formation and poly(cyclopentene sulfone) and poly(bicycloheptene sulfone) have been employed for multilayer integrated circuit mask formation.
In general, the surface relief patterns that are formed in the poly(olefin sulfones) have not been found transferrable to a metal surface by use of sputter etching or ion milling operations wherein material is eroded from the relief pattern surface by ion bombardment. This is a disadvantage in many applications such as audio/video recording where a surface relief pattern which is recorded on a polymeric material must be subsequently transferred onto a metal surface which is employed as a master for stamping the surface relief pattern in large quantities of vinyl discs.
The sputter etching of poly(styrene sulfone) has been described by M. J. Bowden and L. G. Thompson, Journal of the Electrochemical Society, 121, 1620 (1974). This is a relatively insensitive poly(olefin sulfone), however, which does not form surface relief patterns with sharp edge definition. Other of the more sensitive poly(olefin sulfones), such as poly(1-methyl-1-cyclopentene sulfone), which do form the sharp edge definition required for such applications as audio/video recording, have previously not been found sputter etchable. These poly(olefin sulfones) are either highly reactive and initially degrade during a sputter etching cycle, with a corresponding distortion of the surface relief pattern, or they begin to crosslink and form a highly stable residual polymer which is extremely difficult to remove after the sputter etching cycle has been completed. It has been desired to transfer surface relief patterns from poly(olefin sulfone) layers to metal surfaces by sputter etching without the above mentioned disadvantages.